1. Field of the Invention
This invention pertains to a method and apparatus for treating obesity. More particularly, this invention pertains to an apparatus and method for treating obesity with an implant in the gastrointestinal system to alter at least one of satiety, absorption and digestion.
2. Description of Prior Art
A. Obesity as a World-Wide Health Dilemma
Morbid obesity and its concurrent health risks (including diabetes, heart disease and other ailments) are of near-epidemic proportions in industrialized societies. A wide variety of treatments have been proposed and attempted to treat morbid obesity with a wide variety of efficacy and associated morbidity. These treatments include techniques to reduce stomach volume, alter gastric and intestinal motility, and alter the absorption of nutrients in the small intestine.
Clearly, obesity is a complex disease having physiologic, social and psychological components which are not fully understood. The complex nature and the enormous societal implication of obesity require a wide variety of treatment options be available to permit a physician to select a most appropriate option for a particular patient.
Even if all treatments were proven effective, no one treatment can meet the clinical needs presented by a diverse population. For example, current bariatric surgeries, such as the Roux-en-Y procedure as will be described, is not considered suitable for only so-called mildly obese patients (e.g., those with a Body Mass Index less than 35). Also, for extremely obese patients, operative risks may make this procedure undesirable.
Less invasive procedures (such as gastric banding, as will be described) have reduced surgical risk. Unfortunately, they suffer from reduced efficacy (and they are not without risks). Further, efficacy may be culturally biased. Namely, gastric banding studies show reduced efficacy in North American patients compared to European patients.
B. Selected Obesity Treatments
a. Surgical Options (Non-Device)
i. Gastric Volume Reduction
Surgical approaches to gastric volume reduction include minimally invasive surgery, open surgery and endoscopic approaches to gastric volume reduction. Many such procedures have been tried and some have been abandoned due to lack of efficacy or unacceptable morbidity and mortality.
The gastric volume reduction procedures include vertical and horizontal gastroplasty in which sutures, staples or other fixation devices are used to join opposing surfaces of the stomach to create a reduced volume pouch and thereby reduce caloric intake.
Gastric stapling, as used herein, refers to staples or stitches in the stomach to reduce stomach size. These include horizontal gastroplasty and vertical gastroplasty.
Surgical gastric volume reduction is focused on reducing the fundus to induce satiety. Recent studies suggest antral volume more directly influences satiety. Strum, et al., “Energy Intake and Appetite are Related to Antral Area in Healthy Young and Older Subjects”, American Journal of Clinical Nutrition, 80 (3), pp. 656-657 (2004).
Less invasive techniques for restricting the volume of the stomach also include a gastric partition in which the stomach wall is endoscopically cinched together to form a reduced size pouch. The cinching is performed using commercially available products such as the Bard EndoCinch™ and the Wilson-Cook Sew-Right™ cinching equipment. Such surgical equipment is generally described in U.S. Pat. No. 5,088,979 to Filipi et al. issued Feb. 18, 1992; U.S. Pat. No. 6,302,917 to Dua et al. issued Oct. 16, 2001 or PCT International Publication No. WO 01/89393 published Nov. 29, 2001.
It has been recognized that gastric volume reduction does not address all mechanisms associated with obesity. For example, patients with gastric volume reduction can defeat the effectiveness of the gastric volume reduction by modifying eating habits. For instance, a patient may graze continuously on small volume, high caloric food or may replace solid foods with high caloric liquid foods.
ii. Surgeries with Malabsorptive Components
To address deficiencies associated with gastric volume reduction, treatments have been suggested and developed for reducing the amount of nutrient absorption in the small intestine (particularly in the upper and middle portions of the small intestine—the duodenum and jejunum, respectively).
In the duodenum, ducts from the pancreas and gall bladder discharge into the small intestine through small protrusions referred to as papilla. Commonly, pancreatic exocrine secretions (“PES”) flow from the pancreas in a pancreatic duct. Similarly, bile from the gall bladder flows through a bile duct. These ducts merge to form a common duct with discharges through a papilla into the duodenum. In some patients, the bile duct and pancreatic duct do not merge. They separately discharge into the duodenum at separate papilla which, usually, are in close proximity to one another.
Techniques to reduce nutrient absorption (commonly referred to as malabsorption treatments) include drug therapies for reducing lipids absorption. Such drug therapies have uncomfortable side effects, which can discourage a patient from complying with the drug therapy.
Other malabsorption treatments include surgical techniques for rerouting the intestinal system to bypass an extended portion of the small intestine. These include a so-called jejunoileal bypass. Not commonly used due to unacceptable mortality rates, a jejunoileal bypass would result in effective weight loss. Other techniques include the gastric bypass (or Roux-en Y) and duodenal switch. In both of these procedures, a large segment (e.g., in excess of 100 cm) of the small intestine (including the duodenum) are bypassed so that food content is rerouted from a small pouch formed in the upper portion of the stomach to the jejunum. As a result, the absorptive length of the small intestine is significantly shortened thereby reducing the amount of nutrients which are absorbed into the body and which support or lead to weight gain. These procedures combine the benefits of gastric volume reduction with malabsorption. Unfortunately, such surgical procedures are extremely invasive.
b. Implantable Mechanical Devices
i. Gastric Volume and Delayed Gastric Emptying